Successful events, come from successful training, you need to train to increase your fitness, constantly creating stimulus on your body to build bigger muscles, more efficient engines and everything it takes, but not so much stimulus that your body is so damaged it takes a long time to rebuild, or you get into a chronic fatigue situation. At the same time your body is incredibly lazy, and if you don't work it more than its current level, it just sits there content that it's fit enough for the demands.

So the goal is to balance increasing the good stress that builds fitness, but limits the bad stress that stops you training, and maybe even worse knocks you out for months. There's also another side of successful events, that of being not so fatigued from the recent training that you're literally too tired out and damaged to do well. Essentially, this is often expressed as

Form = Fitness - Fatigue.

So how do you manage this? Lots of ways, but the geeky way is to evaluate each workout as to how much fatigue it caused you and how much fitness it will reward you with in the future, and then average out all the workouts to come out with some numbers which tell you your form, your fatigue and your fitness.

Training is essentially a mix of frequency, intensity and duration, but how do you compare different workouts - say five mile repeats at a high intensity, a 10 mile tempo run, or an easier 15miles. Which was harder, which was more useful training, does it even make sense to compare them? I think it does, and if not, you couldn't evaluate more than one session anyway, so we're going to give each workout a score.

Measuring duration sounds pretty easy - you need a watch. The only question becomes what to do with time when you stop, should the time you spend stopped be counted as part of a workout.

Measuring Intensity

Intensity is harder, and measuring intensity is the fundamental problem of scoring a workout.

For cycling, if you have a power meter, you can measure intensity pretty directly by the power you produce, this is how Training Peaks and WKO+ does it, using the ratio of the Normalized Power for the ride to your FTP to get your "intensity factor" to produce the Training Stress Score (IF^2 * duration).

For running, on flat, consistent ground, pace is a very good measure of intensity, and WKO+ / Training Peaks again uses this, however it attempts to deal with hills by creating a "Normalized Graded Pace" for your run as if it was on flat ground. And uses this pace relative to your Threshold pace for creating the intensity factor. [*] The big problem with this is ground surface, running in mud, track or tarmac is completely different and using pace has no way to address this, so it'll never give you good results for cross country.

For both running and cycling heart rate shows a strong correlation with intensity, it can be depressed for various reasons, it falls down particularly at discerning between near maximal efforts, but there's still a very strong correlation. Heart Rate response is not linear though - progressively more stress is done at the higher heart rates than at the lower ones, so you need to scale the intensity with the effort. This has been called training impulse or TRIMP The scaling is generally designed to mirror the blood lactate response of a person (the WKO Power model is similarly designed, being inspired by this TRIMP model.)

For triathletes, because of the problem of using pace for running, I very much advocate using Heart Rate, all of the measures of intensity suffer deficiencies, but at least if you use HR the deficiencies are the same between running and cycling and you won't get confused. Using other measures too when you have the data and comparing the values (relative, not necessarily absolute, since the scales are arbitrary) can be helpful at highlight outliers which you will get, where tough sessions, or easy sessions get very surprising scores.

Another problem with the Power and Pace model of intensity is that it's highly dependant on accurate determination of your threshold power and pace, which are volatile targets, hopefully improving considerably as you train, so you can end up with inflated scores before you realise your thresholds have changed. In established athletes with pretty stable values this is less of a problem, in less trained people improving rapidly it's more of a problem.

CTL, ATL and TSB

Once you have your score for an individual session, you need to mix them together to track your Fitness, and your Fatigue. Your fitness is simply all your workouts for a recent time combined together to create a score for today, your fatigue is the same. The difference being the time period that you measure for. To combine the workouts, rather than a simple average it's a weighted average so that the more recent training is worth more than older training. ie the fatigue caused by yesterdays workout is more than last weeks workout.

The fatigue - the average of your recent Training Scores, is called your ATL (Acute Training Load), and typically set up to respond to the previous 5-15 days of training.

The fitness - the average of your longer Training Scores, is called your CTL (Chronic Training Load), and typically set up to respond to the previous 6 weeks of training.

The form - the difference between your Fitness and your Fatigue, is called your TSB (Training Stress Balance) and is simply the difference between your CTL and ATL.

When your ATL is higher than your CTL, you're likely fatigued, and the larger negative the TSB is the more fatigued you are. When it's positive you're likely in good form. However, if it's largely positive, that can only have happened if you've severely reduced or stopped your training, so whilst you may be very un-fatigued, you'll also not be very fit.

Automating the calculation

Raceday and WKO track this based on power and pace for running and cycling, Golden Cheetah does it for cycling using power, and the general principles are the same as below, but as I recommended Heart Rate, I'm going to recommend the Training Load Plugin in SportTracks. It will use Power like the others, but by default it uses Heart Rate.

Because it uses HR, you need to configure it. First you need to ensure that you have your HR zones configured and they are reasonably right for you, the ST forum has a little info on this. Personally, I use 6 zones, zone 0 for essentially resting, HR below 103, and a classic Zones 1-5, but you can do whatever you want, so long as the zones reasonably match your HR profile.

You can of course have different HR zones for Cycling and running, or indeed any other sport. Once your HR zones are set up, you also need to set up the factors in Training Load to reflect the different intensities. Again here are mine:

The important fact is that the values get progressively bigger as the HR values get larger, so 1 minute at a high HR contributes more to your score than 1 minute at a lower HR. My values for running are different:

They're all higher, this is because for me, running causes considerably more stress, it hurts the muscles more etc, so I want it to contribute a higher value to the ATL than otherwise.

The result, the shiny graphs

The result is some graphs, showing how your training load has changed over the past (click for larger view)

As you can see from the graph, which is my training since March 2008, pretty much when I returned to training as a slow, overweight, average mid 30's geek. The blue shaded area is my CTL, as you can see it rose gradually into the 60's, declined throughout the summer and then rose again as I trained for a marathon - the large bar showing a large TSS in Nov 2008. You can see the taper before the marathon as the red line - showing ATL - drops below the blue immediately before the event.

2009 was much more up and down, as I aimlessly cycle raced, but maintained a general higher fitness (ie more training!) than I did in 2008, and I'm currently extremely fatigued and with a high CTL - that's from 10 days and 41 hours of training in Lanzarote which I've just returned from.

You can use the CTL and TSB to predict performance, you're likely to do very well when your TSB is near 0, it may be that you do best with a little -ve or a little +ve. People are different, and events are different, many people find with intense events a small -ve TSB is advantageous.

The Problem of Specificity

All training isn't equal of course, and CTL/ATL and TSB, is only relevant if the training is appropriate to your event, or specific as it's commonly known. If you look at my graph above and look at the high training load I had in June, you'd think I could've run a good strong 10km race. However, I couldn't, and if you look again just for running, you'll see why.

This clearly shows running is pretty much a winter sport for me (although the big rise in October 2009 was actually in Hawaii when I didn't have a bike) and my Sport Specific CTL in running is tiny during the summer, I barely run once or twice a month.

This just means, whilst you can use overall ATL as a good guide for if you're overtrained, or undertrained etc. It doesn't remove you of the need to keep your workouts relevant to your event.

Does it matter how accurate the factors are?

It doesn't actually matter if you get the numbers exactly right, since the important things are the shape and patterns, not the absolute numbers. Generally though people try and calibrate it such that 100 is 1 hour all out.

Another thing to remember is that you're measuring training stress, so if you increase the duration of the workout but aren't training during it, then it's important that this isn't counted in the final result. That's why there's a zone 0 in my HR factors, this is another problem with TSS used in Training Peaks and WKO, it's inflated by stop time, or long descents where you're essentially doing nothing. Sixty minutes climbing Alp d'Huez and then Twenty minutes descending never pedalling should not actually give you any more training stress than sixty minutes climbing and twenty minutes sitting on a coach driving down. So you need to be a little careful if you use power to avoid inflating your TSS via duration at an intensity which isn't really a workout.

[*] WKO also introduces a fudge factor whereby running is worth 10% more than cycling, this is similar to my increasing the factors in the training load plugin.

Interesting that you're recommending HR to monitor training stress for Triathletes. I'd guess at the least it opens things up to more people to use this approach. What're your thoughts on swimming though? Pace seems the easiest method of assessing stress for a swim session. Admittedly I'm still not scoring any kind of TSS for the swim.

I've started playing about planning my training for Lanzarote by estimating TSS for all my planned sessions and seeing how the PMC should look. Should let me build up CTL and keep a watch on periods of negative TSB.

Hi jibberjim. Thanks for the write up. I have had a power meter since santa claus dropped down my chimney and have been using WKO+ for the data analysing. I find the cycling stuff brilliant and the way the programme tracks my TSB really does match the way I actually feel.

I find the running feature very annoying though. It will not give me a score when I run on the treadmill and as you point out there are fudge factors for elevation and nothing for differing surfaces. Don't even mention swimming!!!! If the running aspect could be improved and the swimming factor fudged in there some how I think it would be a very good training chart for everyone to use. I have never used SportTracks before but will give it a whirl over the next few weeks now you have mentioned it. One question - have you any idea if the scores from sprottracks could be transferred between programmes? For instance, I did a treadmill session last night that I cannot get a TSS for in WKO - if sporttracks gives me a score can I put that into WKO+? Seen as I have a lactate lab test for HR the scores I get should be fairly accurate.

i like the caveat about overinflating the numbers when your not 'working' on a bike i.e riding up a hill for 60 and essentially freewheeling down the otherside for x amount of time

I thought that is what normalised power did? Its the figure I use anyway - never bother looking at average power TBH.

NP doesn't do enough to bring down the file. If you have WKO, find a ride where you did lots of stopping, or descending with zero power, and highlight the stopped periods and use the CUT feature to remove the stopped time / descending time. You'll see your NP will rise slightly, but your NP will reduce even further.

Here's a 6 1/2 hour ride, which included a 30 minute stop (eating potatoes in the cafe at the top of the switchbacks above Haria, yum!) and lots of descending where I was doing 0 watts, and a few other stops to refill water, pee etc. Removing the stops, and the long descents where my HR didn't go above 100 (walking around the shops rate)

You can see that I got 13% more TSS from the ride simply from stops and descending. That's despite the NP being higher in the stopped riding situation. It's simply not enough to make up for the difference in time.

If you're consistent in your training, then it doesn't matter too much, ie you always end up with the same proportion of stopped time then it will probably be okay - the important thing is the shape as I said rather than absolute values. But if you're trying to compare a few 1 hour rides with 1 longer ride, you can end up with the longer ride with more stopping appearing much more valuable than you think.
_________________Jibbering Sports Stuff

What're your thoughts on swimming though? Pace seems the easiest method of assessing stress for a swim session. Admittedly I'm still not scoring any kind of TSS for the swim.

For a lot of folk swimming I think can be reasonably ignored for a couple of reasons, firstly it's a relatively small amount of the overall stress you're getting - it's not hard on you and it doesn't transfer fitness to the run/bike much at all. So I think it's okay to "ignore". However you could score it simply with an estimate (RPE*duration etc.) or there is the approach in RaceDay which we talked about earlier on TriTalk - http://jibbering.com/sports/swimscore.html

But with the lack of transfer to the other sports, and the very different nature of fatigue it gives will likely not make it too relevant, and just lift your numbers without really providing more information.
_________________Jibbering Sports Stuff

Last edited by jibberjim on Thu Mar 11, 2010 11:24 am; edited 1 time in total

One question - have you any idea if the scores from sprottracks could be transferred between programmes? For instance, I did a treadmill session last night that I cannot get a TSS for in WKO - if sporttracks gives me a score can I put that into WKO+?

Certainly, you can override the TSS/TRIMP values in both programs, so taking one from ST to WKO+ will be no problem. The only caveat is that then the absolute numbers, rather than just the shape starts to become relevant so you need to make sure the numbers correlate pretty well in absolute numbers too. You can "calibrate" that with some runs that WKO does do well on - 10km on the track say _________________Jibbering Sports Stuff

Will get myself into sporttracks ASAP. I have actually been on a pretty steep learning curve. Since Xmas I have had to learn how to use an SRM, Garmion 305, associated software, WKO+ and then learn about the various mathmatical stuff in WKO so I can understand and interpret the data. Its only in the last couple of weeks I have actually been contemplating running scores and the like. In reality I feel I have only just acquired enough data to really make some good guesstimates as to where my training is going. You obviously have lots of data and its great to get feedback from your experience.

As for the swimming I think I will worry about that when I have the running figures sorted. It will probably take me a few weeks to get into sprottracks and start getting data out the other end

Very interesting post and a topic that has been the subject of a steep learning curve for me in recent months since I started using the Training Load plugin. On the subject of plugs (!) SportTracks is to my mind amazing and should be top of everyoneís list for tracking training. The functionality and level of customisation is truly mind boggling for something thatís free. And with the TL plugin, it takes the whole experience to a new level. AnywayÖ Iím very much still at the learning stage so just some of my thoughts and questions:

- picking the right intensity factors for activities has been a bit of trial and error for me. Like Jim, Iíve followed the path of higher numbers for running than cycling, due to additional stresses. Canít remember my exact numbers off hand but will certainly see how they compare with Jimís when I get home. Given that I borrowed some of the principles from Jimís website in forming the numbers (for which, many thanks!), they might be pretty similar. But as you say, itís mostly about relative and not absolute values, as long as inputs are consistent
- swimming for me is my weakest discipline and swim sets can sometimes be my hardest weekly sessions in terms of RPE. I therefore like to record TSS for these sessions in order to track overall fatigue / fitness. In any event, itís easy to filter by activity so I donít think it really matters. Iíve been following a simple approach for estimating stress where TRIMP = number of minutes of activity. a 90 minute set therefore gives a score of 90. not very scientific but again fairly consistent over time.
- The idea of a ďzeroĒ zone to cover stops, downhills etc. is a good one I think and one I think Iíll build into my zones. Otherwise, as has happened to me, a 4 hour easy social ride with lots of waiting around at hill tops etc can result in an inflated TRIMP value.

Iíd be interested to hear if anyone is using TL as a predictive tool, as suggested by Russ. Iím coming to the meaty end of a training plan for the London marathon and it might be interesting to input my predicted TRIMP scores for planned sessions all the way to race date and thereby get a picture of how well my taper looks in reducing fatigue (ATL) and increasing form (TSB) and whether it needs adjusting. I know the Training Influence curve is supposed to help with this but doesnít break it down to the individual session level.

JJ,
Thanks, that is one hell of a post! It's going to take a while to digest all that... perhaps I'll leave it to my rest week It will be somthing I look at and try some point in the future.
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